Matt e Tripping

[AndyEVTM3]

Apologies if this is an old problem.

So I’ve had a Gen 3 wall connector fitted with a matt:e unit.

All good except when there is some load on the house the incoming voltage is pulled down from about 220v to about 212v. Consequently the Matt e unit trips on low voltage as it thinks there is a neutral fault, my house is on a T N CS earthing system. The unit trips even without the car charging.

I contacted UKPN who came out the same night to have a look at the low voltage situation.

Today they have dug up the front garden and swapped my cable to another less loaded phase in the street and changed my incoming cable. All credit to their quick action.

This made a bit of difference but the Matt:e unit still trips even if I reduce the charging current to about 10A.

I will try to do a low current charge tonight when all gone to bed, but don’t hold out much hope.

UKPN say they will see if they can tap up the local transformer voltage.

Real question is, if the network can’t maintain the voltage what options are there for a charger installation.

I’ve heard an separate Earth system with a low resistance Earth rod could be used.

Charging at anything like 30A seems like a fantasy at the moment.

Any advice or expearience greatly received.

Thanks

 

[NewbieT]

As you’ve identified, the alternative is get an earth rod fitted. Shouldn’t be mega bucks.

 

[AndrewGR]

Minimum permitted incoming voltage is 216V in Uk but supplier aims for 240V So I think the OP should keep up the pressure on UKPN. I don’t think it should drop to 212V whilst drawing right up to the supply limit - typically 60-100A.

 

[AndyEVTM3]

The UKPN engineer measured the incomer voltage drop to 208v! at about 19:00 with cookers and heaters on but no charger working.

Obviously the matt:e didn’t stand a chance!

I have actually been impressed with the UKPN response so far, hopefully the massive trench in my front garden will be filled in tomorrow, and they can raise the tap number on the local transformer.

I have no idea what is going to happen on the network when everyone has an EV???

 

[MrBadger]

Low power May also be related to any grid issues due to power lines being out of action because of weather.

 

[qwickshot]

It’s UKPN’s responsibility to fix it, as others have said, keep up with them but as you say, all signs are positive at the moment so it looks like they are on it.

Ultimately it may take some time to sort of something somewhere needs an upgrade but they should fix the issue. Remember, it’s not just you having the issue, every load on that transformer will be impacted if they know it or not.

I’m pretty sure the car will also stop charging if the voltage gets too low as well.

 

[AndyEVTM3]

Last night I tried to charge the car. The house was at minimum load and I set a conservative 13A limit.
Started charging at 00:00 and the car charged without any problems and reached 100% (LFP) at about 05:30.
+65miles.

I noticed that the indicated voltage was 230v.

So thankfully I seem to be able to charge, at least at night, on economy 7 tariff.

Looks like the phase swap has helped, but then the street would have been pretty lightly loaded at this time.

Will up the current again tonight to see how far I can push the UKPN network!

 

[Adopado]

Last night I tried to charge the car. The house was at minimum load and I set a conservative 13A limit.
Started charging at 00:00 and the car charged without any problems and reached 100% (LFP) at about 05:30.
+65miles.

I noticed that the indicated voltage was 230v.

So thankfully I seem to be able to charge, at least at night, on economy 7 tariff.

Looks like the phase swap has helped, but then the street would have been pretty lightly loaded at this time.

Will up the current again tonight to see how far I can push the UKPN network!

If the Matt e device is set to trip when below UK spec minimum voltage then so long as you can hold to at least 216v you should be OK (However, I'm sure there will be many people (who don't have this device) who are successfully charging at lower voltages than that from time to time.)

 

[AndyEVTM3]

Have now done night charges at 13, 15 and 20 A. Without low voltage tripping.

Going to set the wall connector to 25A as it looks like swapping phases seems to have made a difference.

Still got a big hole in the garden though

 

[AndyEVTM3]

Great, successful 25A charge.
Tonight it’s 30A full load.

 

[Adopado]

Great, successful 25A charge.
Tonight it’s 30A full load.

Most domestic EV charge points will do 32A ...

 

[AndyEVTM3]

Most domestic EV charge points will do 32A ...

Agreed, however the installer recommended 30A to give the 32A RCD a bit of leeway.

But then who dares wins...

 

[Adopado]

Agreed, however the installer recommended 30A to give the 32A RCD a bit of leeway.

But then who dares wins...

A 32A RCBO should be able to cope with 32A continuous ... it's a rating and not a trip limit ... if the installer was of the opinion that you would be best to run your charge point at lower amps than its rated capability then he really should have fitted a 40A so you could make use of the full rating of the charging equipment. However, it would be wrong of me to recommend anything other than following the advice of your qualified installer.

 

[AndyEVTM3]

A 32A RCBO should be able to cope with 32A continuous ... it's a rating and not a trip limit ... if the installer was of the opinion that you would be best to run your charge point at lower amps than its rated capability then he really should have fitted a 40A so you could make use of the full rating of the charging equipment. However, it would be wrong of me to recommend anything other than following the advice of your qualified installer.

The installer did give anecdotal evidence of having Matt:e units tripping on overload with a 32A RCD fitted and when supplying a Tesla Gen 3 wall connector.

The box is fitted with a 32A rated RCD. I don’t think a single phase matt:e unit is available with a 40A RCD.

I must admit I’ve never had an RCD running at 100% rating for 5 or 6 hours.

However I totally agree that it should be able to, I think I will give it a go.

 

[Rich Hyde]

I fitted a Garo unit for my Tesla wall connector, it comes with a PEN fault unit fitted which trips at 230v +/- 10% (which is the requirement of 7671 2022 ammendment 2) so 207v to 253v allowable range, this unit was cheaper than the matte and comes with a 40amp 2 pole type A RCBO. I have the opposite problem of high voltage which can spike to as much as 256v a couple of times a day, I have reported this to Northern Power Grid who data logged it for 1 week 6 weeks ago but they have not come back to me despite several calls to customer service for an update. This causes my charging to be interupted if it goes high during my octopus go daily slot, a pain in the arse to be honest if its missed the charge when you need it.

 

[AndyEVTM3]

I fitted a Garo unit for my Tesla wall connector, it comes with a PEN fault unit fitted which trips at 230v +/- 10% (which is the requirement of 7671 2022 ammendment 2) so 207v to 253v allowable range, this unit was cheaper than the matte and comes with a 40amp 2 pole type A RCBO. I have the opposite problem of high voltage which can spike to as much as 256v a couple of times a day, I have reported this to Northern Power Grid who data logged it for 1 week 6 weeks ago but they have not come back to me despite several calls to customer service for an update. This causes my charging to be interupted if it goes high during my octopus go daily slot, a pain in the arse to be honest if its missed the charge when you need it.

Thanks for the info. It looks like the lower setting for the low voltage trip would suit my circumstances.
At the moment night charging is really the only option I.e after midnight.
I’ll look into this, cheers

 

[MrBadger]

I fitted a Garo unit for my Tesla wall connector, it comes with a PEN fault unit fitted which trips at 230v +/- 10% (which is the requirement of 7671 2022 ammendment 2) so 207v to 253v allowable range,

It’s actually -6%/+10% so lower cutoff is 216v or thereabouts.

Edit. May actually have changed so -10% might now be right

 

[AndyEVTM3]

It’s actually -6%/+10% so lower cutoff is 216v or thereabouts.

Ahh... probably no better off with the Garo unit.

 

[AndyEVTM3]

Successfully charged at 30A last night from 00:00.
So probably going to be OK. As I only expect to charge between about 00:00 and 07:00.

Really got a bad feeling about what will happen when all the neighbours have got EVs, UKPN better start installing bigger cables and transformers now.

 

[Rich Hyde]

It’s actually -6%/+10% so lower cutoff is 216v or thereabouts.

Edit. May actually have changed so -10% might now be right

No it definately is 230v +/_ 10% (207v - 253v) for PEN fault detection devices, see Regulation 722.411.4.1 in BS7671, you are getting confused with the UK supply voltage range which is 216.2v to 253v (230v -6% / +10%). The Garo unit would have been better for you Andy but the DNO are legally obliged to supply us with 216.2v to 253v so correct action is for them to sort out the supply to comply with the allowed band. I have been logging mine for 2 months a 5minute intervals and if I get no Joy the next time I call them then unfortunately I will have to log a complaint with OFGEM which can result in the DNO getting a large fine.